1. Field of the Invention
This invention relates to a wrenching tool, and in particular to a hand tool useful for removal of frangible fasteners.
2. Brief Statement of the Prior Art
Frangible fasteners are used extensively in the aerospace industry. These fasteners employ a threaded nut member which has a threaded collar and a distal wrenching ring joined by a neck with a notched section which shears from the collar when the applied torque exceeds a predetermined torsional loading. Often the threaded collar has an upset portion, usually a slightly elliptical shape to provide a frictional spring lock that prevents the fastener from spinning off in the event that the residual tension on the fastener is lost.
These fasteners are applied with power driven, or hand, wrenching tools which engage the distal wrenching ring to apply the threaded collar and twist the wrenching ring from the threaded collar when the predetermined torsional loading is exceeded.
It is frequently desirable to loosen or remove the threaded collar from the assembled fastener. Heretofore, no entirely suitable tool has been devised for this application. The threaded collar commonly has a cylindrical base which tapers into a smaller diameter cylindrical neck. The cylindrical portions of these collars are narrow and are difficult to grasp with conventional tools such a pliers and vise grip clamps, etc. Additionally, the use of non-standard tools for loosening or removing of the frangible fasteners is objectionable as such tools can damage the surfaces of the assembled parts.
A universal wrench has been marketed which uses a socket head with a pivotally attached handle. In this tool, the handle has a jaw end that is received in a slot in the side of the head, and the gripping surface of the tool is thus centrally located within the head. This tool is not suitable for removing the fasteners used in the aerospace industry as narrow collars of the fasteners cannot be readily grasped by this tool.